<HTML>
<HEAD>
<SCRIPT LANGUAGE="JavaScript">
<!--
function Validate(form) {
    var v = new RegExp();
    v.compile("^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$");
    if (!v.test(form["URL"].value)) {
        alert("You must supply a valid URL.");
        return false;
    }
}
//-->
</SCRIPT>
</HEAD>
<BODY>
<FORM NAME="MyForm" ACTION="MyFile.php" METHOD="POST" onSubmit="return Validate(this);">
<INPUT TYPE="TEXT" NAME="URL" VALUE="http://">
<INPUT TYPE="SUBMIT" NAME="SUBMIT" VALUE="SUBMIT">
</FORM>
</BODY>
</HTML>